Re:[Sip-implementors] How does Redirect server treat ACK ?

[Gautham A N]

Hi anand,   a) Does it mean that Redirect returns 3xx for ACK request also? However, this contradicts the basic rule "ACK doesn't generate any response"     An ACK never generates a response. b) Redirect can receive ACK in two ways - acknowledgement of 3xx for INVITE and erroneous ACK. Since redirect is transaction-based, how does it discriminate between those two ACKs.     The ACK has the same CSeq number as the INVITE to which a 3xx was sent. This along with the call leg identifier( the combination of TO, FROM and CALLID)  helps to match the ACK with the corresponding INVITE. If the matching fails, then it concludes that it is an 'erroneous' ACK. Also, since the 3xx response is retransmitted, the Redirect server will be expecting an ACK and thus will have the relevant information about the call leg.     Hope this helps. gautham. _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors